Alloy comprising iron, nickel, chromium, molybdenum



Patented Feb. 12, 1924.

UNITED STATES PATENT OFFICE.

PIERRE GIRIN, OF PARIS, FRANCE, ASSIGNOR TO SOCIETEANONYME DE COMMENTRY,FOURCHAMBAULT & DECAZEVILLE, OF PARIS, FRANCE.

ALLOY COMPRISING IRON, NICKEL, CHROMIUM, MOLYBDENUM.

No Drawing. Original application filed December 9, 1918, Serial No.265,985. Divided and this application filed February 8,

To all whom it may concern:

Be it known that I, PIERRE GIRIN, a citi-' zen of France, and a residentof Paris,

France, have invented new and useful is ralsed from 400 to 500 C. andthe hard 'ness conferred by a suitable tempering disappears at the sametime as the reheating annuls the action of the treatment.

The high speed steels certainly preserve their hardness at a temperaturehigher than the other steels, and after they have been tempered possessa high resistance, even up to a red heat, but besides the drawbacks 2which result from their fragility and difficulties of a practical naturedue to the extremely high temperature of their treatment, they do notpresent the desired stability when the temperature exceeds 600; in fact,not 30 only an accidental excess of temperature beyond the regulatedvalue, but even prolonged ex osure to this temperature produce a graduadisappearance of the initial hardness and a progressive diminution ofresistance. Fi- 5 nally, they are very oxidizable.

In addition, the invention of gas motors, gas turbines and other thermalmachines intended to act above the temperature of red heat, and thediscovery of chemical synthetic 60 processes using at the same time hightemperatures and high pressures, render the realization of a metalpossessing certain qualities at' high temperature extremely desirable.

The present application, which is a divi- 4 sion of my apphcation,Serial No. 265,985, filed December 9, 1918, concerns an alloy of iron,nickel, chromium and molybdenum, and including, perhaps, tungsten orvanadium, cobalt and titanium, easy to obtain in large quantities andcapable of being moulded, or otherwise, forged, rolled, wire drawn,worked, without difliculty, possessing at the tem erature of 800 aresistance almost equivalent to that of cold iron, non-fragile,

1922. Serial No. 535,044.

practically inoxidizable at high temperatures, even in a very oxidizingtemperature, and at the same time possessing properties which arestrictly reversible; by this term I understand that the properties at. agiven temperature depend solely on that temperature and in no way on thepreceding temperatures that havebeen obtained, nor on an exposure moreor less long to the temperature used. The alloy may contain, forexample:

Per cent. Nickel 60 to 70 Chromium 10 to Molybdenum 1 to 3 Manganese 1to 2 Carbon 0.3 to 0.6

Iron forming the remainder.

Certain variations in the composition may fer on the alloy of iron andnickel a very high resistance when heated: I can obtain easily 25 to 35kgs. per sq. mm. with an elastic limit of 20 to 30 kgs. and acoeflicient of elongation of 40 per cent at a temperature of 800, whilestill preserving a total absence of fragility. These additional elementsalso render the alloy extremely resistant to the attack of acid vapours,as well as of hot oxidizing and moist gases. This chemicalunalterability is of the greatest importance for all applications, sinceit not only ensures the metal against corrosion, but also ensures thepreservation of the initial mechanical properties, in contra-distinctionto that whichtakes place with carbon steels which, when heated for along time in an atmosphere rich in hydrogen, finally become decarburizedand lose their solidity.

This alloy is certainly very suitable for the manufacture of gasturbines or for receptacles, employed in chemical industry, forreactions which take place at high temperathre and at high pressure andwhich produce corrosive gases or other substances.

Having thus described the nature of the said inventionand the best meansI know of a carrying the same into practical vefiect, I

claim:

A high nickel ferrous alloy containing nickel, 60 to 70 er cent,chromium, 10 to 15 per cent, molyb enum, 1 to 3 per cent, manganese 1 t02 per cent and carbon, 0.3 to 0.6 per cent, such alloy having atelevated temperatures great mechanical resistance to chemical agents andsusceptible of retaining indefinitely its initial properties,notwithstanding prolonged service.

In testimony whereof I have signed this specification.

PIERRE GIRIN.

